Star Wars Laser Shines Right On Shuttle Target

June 22, 1985|By James Fisher of The Sentinel Staff

CAPE CANAVERAL — Stalking its target with a pulsing beam of blue-green light, a laser successfully tracked the shuttle Discovery Friday as the spaceplane soared through darkness 220 miles above the Hawaiian islands.

It was the first successful space test of Star Wars technology that President Reagan hopes will lead to development of a shield from nuclear missiles.

Television pictures from Discovery were as exciting as a planetarium laser production. The light flickered in the center of a dark field as Tchaikovsky's ''1812 Overture'' thundered majestically in the background.

NASA officials called the test ''a spectacular laser show,'' and Air Force technicians were joyous that the test succeeded so well despite high winds on the island of Maui that threatened to postpone the operation.

''It's a very successful test at this point, as far as we can tell,'' said Army Lt. Col. Lee Delorme, spokesman for the Star Wars program.

The test was first attempted Wednesday but failed when a misprogrammed autopilot flipped the shuttle upside down and backward, pointing an 8-inch reflector in a hatch window toward deep space and out of view of the laser.

After an analysis of Friday's test data, the Air Force may ask for more tracking time today. Discovery also is scheduled today to retrieve a satellite that is scanning the Milky Way for signs of a black hole.

The 4-watt argon laser, beamed in a split second from a ground station on Maui's 9,954-foot Mount Haleakala, tracked the shuttle before dawn for 2 1/ 2 minutes and possibly longer, the Air Force said.

The laser experiment was part of Reagan's Star Wars research program and was the first in a planned series of tests aboard the shuttle.

The laser light was not considered harmful to the astronauts' eyes, but as a precaution Mission Control advised the seven crew members to look at it in quick glances only.

Ground computer commands repeatedly focused the laser tightly on the shuttle and adjusted its aim based on light reflected back from space. The exercise allowed technicians to study the system's tracking capability and the atmosphere's effect on the dispersion of laser light as it beamed toward the shuttle and back.

The repeated adjustments and high winds that buffeted instruments apparently were responsible for the pulsing effect, said Air Force Lt. Col. Tom Meyer.

The test was nearly called off because winds had been gusting up to 55 mph and could have damaged the instruments inside the open observatory dome. However, winds slacked just before the test.

Discovery was first tracked by ground radar as it sped over the horizon in view of Hawaii at 17,400 mph. The radar then signaled the laser's computer, which began its own tracking.

''We have the target in sight,'' mission specialist John Fabian reported as he spotted the laser's flashing glow. ''It's bluish green. . . . It pulsed for a while and locked on steady for some periods.''

The beam was only a quarter of an inch wide as it left the laser, but widened to 30 feet as it traveled 220 miles high to shine against the front half of the shuttle.

The $30,000 pyramid-shaped reflector in the shuttle's window returned some of the light to Earth, a welcome sight to Air Force technicians who had spent the previous 30 hours preparing for the big moment.

A laser beam is produced when electrical energy is applied to gas in a tube enclosed at both ends by mirrors, one more reflective than the other.

The voltage induces electrons to absorb energy, and then release it in the form of photons, the basic unit of light. The trapped photons streak back and forth, striking other electrons and releasing more photons.

In perfect wavelength harmony, the photons become a tidal force that bursts through the less reflective mirror in a narrow beam of the purest light on Earth.

Later Friday the shuttle began firing thrusters to move toward the Spartan satellite in preparation for today's retrieval about 9 a.m.

The satellite was released Thursday on an assignment to search for X- rays streaming from near a suspected black hole at the center of the Milky Way, an area 30,000 light-years away. One light-year is 5.88 trillion miles.